Thread: 200Ah LiFePo4 Auxiliary System

Originally Posted by p38arover

That cost is better than I expected.

My starting battery is 18 months old and is noticeably degraded. When I bought it, I didn't realise it should have been an AGM.

Add to that the two 45Ah deep cycle AGM aux batteries that are the same age and are now of reduced capacity that they struggle the supply just a fridge overnight.

Replacing all within 2 years isn't a good deal compared with your system.

Ron, first off, your batteries should not have died that quickly. How much driving are you doing.

Also, it is morethen likely that you can recover the lost capacity with some sustained overnight charging.

Secondly, if your driving habits are the cause of your battery situation, changing to lithiums is not the answer because they can suffer from the same problems, but they are quicker to fix.

Originally Posted by SeanC

So I ended going with 2 x 100Ah LiFePo4 behind the second row seats and an Odyssey PC1350 as a cranking battery. With only cranking duty hopefully I should get increased life span.

As I was mixing battery types I needed an ignition switched DC2DC charger. So the SC80 has been retired for the moment.

Time will tell if it will be a good investment.

Heard a lot for and against so I decided to give it a go and find out.

LiFePo4 Auxiliary Set-up - Google Photos

Mate, thanks for sharing that — you’ve done exactly what I’ve been thinking about doing. My Optima Yellow Tops are leaving me a little bit unimpressed right now — not holding voltage and the reseller isn’t interested in backing the product.

Do you have any extra photos that show how the batteries are secured? I’ve got Front Runner drawers in the back of my D3 and there’s options for mounting where the third row seats are (if I remove them permanently, which I think I’ll do anyway), or in the space directly behind the second row. I’m keen to see how I can best secure them back there safely.

Cheers,

— Andrew

Originally Posted by ndrew

Mate, thanks for sharing that — you’ve done exactly what I’ve been thinking about doing. My Optima Yellow Tops are leaving me a little bit unimpressed right now — not holding voltage and the reseller isn’t interested in backing the product.

Do you have any extra photos that show how the batteries are secured? I’ve got Front Runner drawers in the back of my D3 and there’s options for mounting where the third row seats are (if I remove them permanently, which I think I’ll do anyway), or in the space directly behind the second row. I’m keen to see how I can best secure them back there safely.

Cheers,

— Andrew

Hi Andrew No other photos yet. Will have a look tomorrow. Pretty confined space with the seats back in.The cargo barrier meant that conventional battery boxes were too high. As you can see the foam flooring was pulled forward so they had a solid base under them. The thought was the foam might allow some movement and the mounts might loosen. The mounting bolts go through the floor and then sealed with silicon. It was a tight fit. Another couple of centimetres in width and I wouldn’t have gotten the seats back in. Without a cargo barrier you could most probably use battery boxes.

Originally Posted by ndrew

Mate, thanks for sharing that — you’ve done exactly what I’ve been thinking about doing. My Optima Yellow Tops are leaving me a little bit unimpressed right now — not holding voltage.

Andrew

Hi Andrew, what is the voltage of your Yellowtops and how are you charging them.

Yellowtops batteries actually offer better charging results than lithium batteries, because to charge lithium batteries properly, you need some form of charging device.

Because Optimas can be charged direct form your alternator, you can charge them from a low state, with as much as 100 amps in the initial state of the charge.

As I posted above, you need at least a 60 amp DC/DC device for charging lithium batteries before you get anywhere near what your Optimas will charge at, when charging direct from an alternator.

PLEASE NOTE, I do not sell Optima batteries but I will soon be selling lithium batteries, so this has nothing to do with being biased but is to do with which type of batteries perform best in a given type of situation.

Usually the cause of low voltage in an Optima is insufficient charging time. So replacing them with lithium batteries most likely, will not resolve the problem.

So again, how are you charging your Yellowtops and what sort of drive times are you doing?

Originally Posted by SeanC

Hi Tim. The DC2DC charger is a 40 amp.

Your pic shows a DC2DC+ I have one & this model will do 50A if the cabling is big enough & you change the settings.

Originally Posted by Milton477

Your pic shows a DC2DC+ I have one & this model will do 50A if the cabling is big enough & you change the settings.

It does say 40+ in the name. Will have to a read through the manual. Thanks for the heads up.

G'day, Tim.

Originally Posted by drivesafe

Hi Andrew, what is the voltage of your Yellowtops and how are you charging them.

I'm having trouble keeping the Yellow Tops above 12.8V for any length of time, with them rapidly dropping to 12.4V or lower with relatively mild use. They're being charged by a Redarc BCDC1225D.

Usually the cause of low voltage in an Optima is insufficient charging time. So replacing them with lithium batteries most likely, will not resolve the problem.

So again, how are you charging your Yellowtops and what sort of drive times are you doing?

I'm not convinced that it's a charging issue. On a 8-hour run to Western New South Wales recently, I immediately checked the voltage once I arrived at my destination and watched it rapidly drop back to 12.8...12.7...12.6 and so on. It's not a linear drop, I have to admit; it seems to drop from 13.1 to 12.8 rapidly and then more slowly from there.

The car also has a 160W solar panel mounted permanently on the roof which runs into the BCDC1225D.

My motivation to changing to lithium is three-fold: one, I'd love a bit more capacity than my two Yellowtops currently provide; two, I'd like something lighter and to free up some space in the engine bay, and; four, I'd like to replace my BCDC1225D with a BMS like the Redarc Manager30.

Cheers,

- Andrew

Originally Posted by ndrew

I'm having trouble keeping the Yellow Tops above 12.8V for any length of time, with them rapidly dropping to 12.4V or lower with relatively mild use. They're being charged by a Redarc BCDC1225D.

I'm not convinced that it's a charging issue. On a 8-hour run to Western New South Wales recently, I immediately checked the voltage once I arrived at my destination and watched it rapidly drop back to 12.8...12.7...12.6 and so on. It's not a linear drop, I have to admit; it seems to drop from 13.1 to 12.8 rapidly and then more slowly from there.
- Andrew

Hi Andrew and I am not going to get into what charges better, while on the road, but when at home, do you use a battery charger to charge them, at any time, when they seem to be low.

From what you are saying, it just sounds like they are not being charged properly because of drive time.

Your one big drive, regardless of whether they are charged by a DC/DC device or direct from an alternator, if your batteries are in a poor condition, one long drive will not fix the problem, but long charging times at home with a battery charger probably will.

The link below will give you an idea of what to do, to improve the capacity and condition of your yellowtops.

Just scroll down to the post on Long Term Battery maintenance.

On-Line auto electrical info